Two Spaces After a Period—The Definitive Guide

When you’re typing, you may out of habit put in an extra space at the end of a sentence; That’s two spaces between the closing punctuation of one sentence and the beginning of the next. Or it may not be out of habit, but rather, on principle. Let’s talk about that principle.

Before common use of the space, early Latin writing ran in a continuous script, a stream of letters, line-breaking often in the middle of (what we call) a word. With the addition of spaces, and later, punctuation, words as we now know them developed, and along with them, sentences, grammar. As to the amount of space between sentences, that would vary by hand and circumstance until moveable type.

And after. You see, spaces come in a variety of standard sizes. The earliest works printed from moveable type were all set in justified columns, meaning that the width of each word space expanded or contracted slightly from the normal word space to fit different numbers of characters per line as needed. In these early samples, the amount of space between sentences ranged from quite wide, to slightly narrower than the space between words. The most obvious reason for using a narrower space here is to maintain an even typographic color, since the period traps quite a lot of negative space on its own. By the late 18th century, conventions favored more generous sentence spacing. My take from all this early letterpress stuff—counting the number of spaces after a period is as pointless in samples of early printing as it is in handwritten manuscripts. This holds up until of course, typewriters.

Published by Anson D. F. Randolph, New York, 1864. The text is a Caslon.

With typewriters, we get three things—unjustified type, fixed-width typefaces, and typists. The first two pertain to our discussion because we can now count precisely the number of spaces after the period. The third, because our usual scheme of submitting something to be published just got another layer. The typewritten page became both an interim format and a final format for papers and books. Scholarly papers, for instance, were submitted as typewritten manuscripts which then did the rounds between editors, and on to typographers, and ultimately, typesetters. In contrast, for some publications, the typewritten page (or a copy of it) was the final. Whether two spaces after a period arose as a standard under the first typing instructors’ imitation of the printed page, or the practice began independently of what came before, is unclear. Ultimately however the question of how to compose the input should be settled by its output.

The common convention for published works today is a single space between sentences.

If you’re submitting your writing to be published, save the typographer the trouble of finding and removing all those additional spaces by not keying them in in the first place. If you’re producing final output on your own (writing for a blog, etc.) the same rule applies.

Unless

Keep putting two spaces in if:

You’re typing on a manual typewriter, or your final output will emulate the look of that of one.

If you’re specifically pursuing a naïve style.

If your style guide requires it.

This last one you should be careful to do begrudgingly, like I do when occasionally required to capitalize the word ‘Internet.’ Which arcane style guide requires two spaces after a period, you ask? APA Style does. MLA, Chicago, and AP have all questioned the usefulness of that second space and decided it’s best to go without.

Hi Seb. It’s as clear-cut as I’d like it to be.
In the piece you link to, the main argument is that the origin of two spaces after a period is probably based on common typographic practice around the time commercial typewriters entered the market en masse. (And that because of this evidence, present typographers should not blame the typewriter for, nor turn their nose up at those who continue to follow this practice.) In my piece I say it may or may not be based on the same common typographic practice, but that ultimately the point of origin is irrelevant. I don’t grant permission to look down on the practice, but rather I explore its legitimate uses.

Interesting, thankyou. I agree that the output determines the choice… I find that virtually all typefaces look great with just one space, but Gill Sans looks like it was designed for two as one space is microscopic.
On a slightly similar topic, I always get a spellcheck warning for thankyou (rather than thank you). I wonder when the consensus might change on that one.